Treatment of the skin with lasers has been the subject of study since the early 1960's. A variety of lasers have been used in dermatologic practice. Lasers are primarily distinguished by the wavelength of the light produced, measured in nanometers, such as the XeF excimer (351 nm), argon (488 nm, 514 nm), ruby (694 nm), Nd:YAG (1060 nm), and CO.sub.2 (10,600 nm) lasers.
More recently, photothermolysis of skin has been demonstrated using xenon fluoride (XeF) laser and Q-switched ruby laser pulses. It has been discovered that radiation from Q-switched ruby lasers deeply penetrates the epidermis. This is accomplished, in part, by choosing a wavelength that is well absorbed by the specified target cells, with minimal absorption by adjacent tissues. One particular study entitled "Treatment of Epidermal Pigmented Lesions With the Frequency-Doubled Q-Switched Nd:YAG Laser", Arch. Dermatology, 130:1515-1519 (1994), teaches the removal of benign epidermal pigmented lesions through application of a frequency-doubled Q-switched Nd:YAG laser (532 nm). By selecting a laser capable of producing a wavelength strongly absorbed by melanin and controlling the pulse duration of the laser, the pigmented lesions are effectively targeted and the melanosomes destroyed.
It has been further discovered that the selective application of ruby red laser energy to hair will cause significant follicular damage to the extent that the hair will fall out. Applicants' previous U.S. Pat. No. 5,509,192, incorporated herein by reference, discloses a method whereby a ruby red laser is used to apply a pulse of laser energy to a single hair follicle, causing papilla damage and the resultant death of the follicle.
It has been proposed to apply specific types of contaminants to a section of the skin containing hair which is to be irradiated. The contaminant is selected on the basis of its ability to absorb a specific frequency band of light. U.S. Pat. Nos. 5,425,728 and 5,226,907 to Tankovich teach the application of a contaminant to the skin for purposes of infiltrating the hair duct itself. This prior art method does not teach or suggest the application of a contaminant to the surrounding structures of the hair i.e. the sebaceous gland, papilla or cappillaries, each of which are essential to hair growth and therefore permit regrowth following irradiation. The taught contaminants do not in and of themselves have the ability to be absorbed within these peripheral but essential structures of the hair. Because these regions are not treated with the contaminant, they remain unaffected following irradiation and regrowth of the hair will almost always occur.
In view of the above, a need has existed in the art for a more effective method of depiliation providing lasting results through application of a wavelenth absorbing contaminant/amplifier compound adapted to accumulate within the dermis surrounding each hair follicle and respective papilla.